For an EV shell battery, in order to solve overcharge problem, a solution generally adopted in the industry is to cut off a main circuit of the battery before cell failure, which prevents the battery from being continuously charged, so as to guarantee safety of the battery. A common structure is that: a current interrupt device is connected between a first terminal and an electrode assembly, and a second terminal is always electrically insulated from the current interrupt device. When the battery is overcharged, gas is generated from the interior, and when internal gas pressure increases to a certain value, the current interrupt device is activated to make the first terminal be electrically disconnected from the electrode assembly, thereby preventing the battery from being continuously charged. In such a structure, in order to prevent the current interrupt device from directly contacting and being electrically connected with a top cover plate, usually an insulating piece is arranged between the current interrupt device and the top cover plate. In order to guarantee good sealing effect of the battery, one sealing piece is arranged at a side of the insulating piece close to the interior of the battery, and another sealing piece is arranged between the insulating piece and the current interrupt device.
However, for the above-mentioned sealing piece, since the sealing piece is located in the interior of the battery and the battery is full of electrolyte, resulting in a large contacting area between the sealing piece and the electrolyte, during a long period of use, the sealing piece is easily decomposed, and when the battery is working, heat produced by the cell in the battery may easily soften the sealing piece, thereby reducing the sealing effect of the sealing piece, leading to leakage of the electrolyte in a serious case, which reduces reliability of the battery.